Insane.

Honestly, i think i'm going mad, i think i'm loosing my mind. And i'm not just saying that. After such a long time of being depressed, self harming and mentally torturing myself i have been acting very un-like me, i mean VERY un-like me.
One minute i'll be looking at myself in the mirror, the next i am tearing at my skin, literally trying to tear it off. About 2 seconds later i finally realize what i'm doing but i'm so shocked i'm doing it, because i didn't make myself do it, i was completely unaware of what was happening.
It all happens at about 2am every night, its like i change bodies because ill start rocking on my floor, and talking to myself, at one point i shouted at the mirror 'this is all your fault' and i actually scared myself with how aggressive i was.
This might be common, a feeling of insanity but this is making me worried about my mental heath because this is very unusual to me and i don't like it. i don't like what is happening to me.
Throughout the day i will reenact horrible things in my head, like a devil coming inside me, or me being took away to a mental hospital and other weird things like that, i don't know if this is normal for depressed people but i just want some answers, i want to know this isn't just me who feels like I've lost my mind, answer responses i get will be much appreciated.
I just want to know that i'm O.K.

That doesn't sound normal. Some depressed people feel like they are loosing their mind sometimes, even I do that, but what you are explaining sounds more serious. You should definately talk to someone about it, maybe go to your doctor and he'll help you. Feeling like you are loosing your mind is not a good thing at all, and chances are that if you don't seek hep it will just get worse.